Ain't no thing
by VictoriaPyrrhi
Summary: This is just two people who occasionally have sex like two normal consenting adults. It isn't a habit. It isn't a thing. College era Casey/Derek.


**A/N:** A little deviation from my normal fare; enjoy this stint into the Life with Derek fandom, and you all can blame Lueur d' Laube and Maesnapdragon!

* * *

This isn't a thing.

It isn't a_ thing_ because she refuses to let it be a_ thing_. This is just two people who occasionally have sex like two normal consenting adults. It isn't a habit. It isn't a_ thing_.

Really.

She thinks this even as she's pushing him against the wall outside of her psych class, and his hands are fisting into the material of her shirt where it rests against her hips, and he's moving her out of the hallway and into this little alcove, her blunt nails biting into tensed biceps. They've made use of this particular alcove more than once, but that doesn't make it a habit, just...convenient. And just because she's already got one hand tangled in his hair, and he's got one deft hand underneath her skirt- a skirt that she totally did not in any way, shape, or form pick out specifically for such an eventuality- that doesn't mean this is anything more than a coincidence.

The fact that he's already hard against her other hand doesn't really mean anything either. He's a _guy_, college aged, and he's always had a more than healthy sex drive. It's certainly got nothing to do with this not-routine they've not-fallen into._ He's_ certainly not going to be the one to tell her that one look from her is enough to make him pop a boner_ every_ time, that he wakes up from dreams of her sticky with sweat and other things like he's fifteen years old again and he can still hear her in the next room over.

She doesn't linger on the implications that they're doing this _again_, and outside of her psych class no less. There are words like_ transference_ and _codependance_ dancing through her brain, but she pushes them away under the feel of his palm against the skin of her hip and his fingertips as they edge past the elastic of her panties. She gasps, and it's swallowed in his skin, goosebumps pebbling under her mouth. One deft hand already has his belt buckle undone, and the sound of his zipper is loud in her ears, but not as loud as his moan. It's quick, and she's not sure if it's the result of too much pent up energy exploding all at once, or if it's something else entirely. She balks at the idea that they just know each other well enough that their climaxes are almost simultaneous.

They go their separate ways when they're done; she straightens her skirt and tries to make her legs stop shaking. He takes a long moment to cringe back into his pants and try to catch his breath. He's got one impending problem taken care of, but he doesn't know what to do about the fact that every time he blinks, all he can see is the way her face scrunches up and the piercing blue of her eyes meeting his as she comes undone around his fingers.

This isn't a_ thing_, he wants to say, and he knows at least that she would agree. It might be the first thing that they'd both agree on without hesitation, and isn't_ that_ just the worst kind of fucked up? He almost wants to see the look on their parents' faces when they discover just _what_ their eldest children finally agree on.

"Tonight?" he finds himself asking with precisely _no_ input from his brain.

She stops and turns, and he wants to do_ something_ to her hair with the way it's hanging there, just slightly mussed. "What?"

"Studying."

She narrows her eyes and he smirks. And this isn't a_ thing_ so really, there's no reason why she should say no because god knows he needs the help, and it's better than having to track him down. "You're giving up easily," she finally manages.

"Coach is really strict about that scholarship. Who better to help me out than nobody's favorite keener?" She flicks her hair over her shoulder and he doesn't watch it no, not at all.

"You're buying dinner," she says, and then she's gone, and he is just as adamantly not watching the way her ass twitches in his favorite skirt because he doesn't _have_ a favorite skirt of hers. _That_ would be crossing a line.

* * *

The first time it happens is so cliche it makes him want to tear his hair out. But that's only after the fact when he sits down and lets himself think about it (which really only happened the once because he doesn't do _thinking_). They had just gotten to Queens- parentals gone not even a full day and she's already knocking on the door to his dorm room and he doesn't fully understand why he doesn't just_ ignore_ her, but hell. He can do a lot of things to Casey, but ignoring her has never been one of them.

He lets her in with a sneer, and she responds with a snarl and that strange, off-kilter feeling that's been lingering since his dad and Nora left eases a little.

"Honestly, you haven't been here for a full day and your room already looks like a pigsty. You're disgusting, Derek-"

"You know, you don't_ have_ to be here. In fact, feel free to exit any time, Spacey."

She sniffs, but doesn't really have a response, and he thinks about pushing the issue, but he's kind of glad sort of maybe that she's here (that_ she_ came to_ him_), and so instead he just turns the TV on and hops up onto his single dorm bed and ignores her. He watches as she looks at his desk chair (messy and covered with clothing) and then at his bed (messy and covered with him).

"Move over," she demands, and he gives her a blank stare until she hops up beside him, and he's scowling at her. He doesn't move because she asked, and she growls a little and slaps at him. He slaps backs. "Derek, scoot over." It's not quite a whine.

"No, it's my bed. Go watch TV in your room."

She does pout now, and he struggles to hide a grin. "I can't. My roommate didn't bring the TV like she said she would."

"Well that's just too bad, isn't it?" He flicks the channel over to baseball- something he knows she hates even more than football or hockey and counts down.

"Der-_rek_!"

"We're not at home anymore, Case," he taunts. "I don't have to share, and you can't make me change the station."

"Wanna_ bet_," she growls and he totally does not smile as she launches herself at him, one hand reaching for the remote, and it's so familiar and yet so different because no one's going to stop them here. He holds the remote away from her grasping hands, and she pays no mind to the fact that she's climbing all over him in her tiny navy shorts and yellow tank top, or the way his hand slips under her shirt to tickle her side.

She snorts a laugh and squirms away, only to renew her efforts the moment she sees him looking at her triumphantly. They roll and twist and he tries to pretend that those are not her breasts pressing into his cheek, and she doesn't question the fact that his hand clutching her hip keeps her from rolling off the edge of the narrow bed. The remote slips from his grasp, and they both hear it clatter on the university issue tile, but neither stops struggling. Her fists beat against his chest and back and he pulls at her hair and slaps at the skin exposed as her shirt rides up.

Except it's not really slapping anymore if his fingers are running across her skin, hot and rough, and she's not punching so much as she has his shirt clenched in one hand and his hair tangled in the other and they're both realizing that this is usually the point at which they're pulled apart by their parents and scolded for fighting.

Derek's the first one to break past the moment; Casey's pinned beneath him and he's got the crook of her neck centimeters from his mouth and he can feel her breath, hot and heavy and fast against his ear. And_ fuck_, it's right _there_ and no one is going to stop him except maybe Casey, but she hasn't yet and then his teeth sink delicately into her neck and he can taste the salt of her sweat and something that's just_ Casey_ and he figures while he waits for the slap, he can at least enjoy this.

Except she's not slapping. She's turning her head and giving him better access and her teeth are nipping at his earlobe and he didn't know that was one of his turn-ons until now. She adjusts her grip on his shirt, pulling him closer and he swears to god she deliberately grazed his nipple and he groans against her skin, rocking against her. She pushes back, hips rocking delicious friction and this is the push-pull that he craves and god it's even better with her lips and touch than it is with her words.

"You're so. Fucking. Obnoxious," she says, punctuating each word with a bite, working her way from his jaw to his collarbone. He's not sure why he's still wearing a shirt, and she seems to read his mind in agreement because she's ripping the hem upward, mouth leaving him long enough to throw the shirt across his dorm room.

"I'm obnoxious? You're such a fucking _princess_," he hisses it into her mouth, and he stops any further complaint with a hard kiss that she arches into. "Gotta have everything _your_ way." He bites the top of her breast, her tank top completely ineffective, and she _mewls_.

"I can't help if I'm always right," she gasps, and he pops the button on those damn shorts.

"Wrong, princess," he mutters, edging his fingers past her panties, and her voice stutters for a moment. She's wet and warm and it feels like winning because she's not talking and_ he's_ the reason, and then she's got clever fingers down the front of his jeans, grasping him through the cotton of his boxers and winning and losing are such relative terms, really.

The real kicker is, they don't even have sex. Not the first time, anyway. He brings her to orgasm with talented fingers and his voice a low murmur against her ear, and the combination is too much for her to bear as she strokes him off with a skill that makes his blood boil. She's_ Casey_ and she shouldn't know that trick with her wrist and _god_ what else does she know?

He expects awkwardness because this is Casey and_ him_ and they've just done something that he can't quite qualify. She's more than a quick bit of fun, he knows that- there's enough baggage there to fill a 747, and yet regret doesn't even enter into the equation because he's kind of been wanting to do that since they were 15 and locked in a bathroom together and she'd challenged him with bright, unafraid eyes. What he expects is for her to pull away because Casey's a good girl, and good girls don't do things like jack off their step-brothers on their first night away from home.

Instead, she stretches underneath him and asks if he has a tissue. She doesn't try to hide the panic in her eyes; she's not sure that she could, but she feels _good_- better than she has in ages, and she doesn't regret it enough to let Derek win and chase her away with awkwardness. He smiles, and it's open and genuine in a way that takes her breath away.

They clean up and end up watching some neutral show that neither can remember, and she's startled by how ultimately ok she is with this. When she goes to leave, she says "Thank you," and she means one thing, but the slow grin that spreads across his face means something else entirely.

"Anytime," he says, and he hopes that she understands he means it.

* * *

They end up sharing a few classes, and they argue about studying and friends, and she hits him and he laughs at her and everything is so normal it hurts. If they share a few too long glances, or Derek gets a little too close to her personal space, well, that's really nothing new at all. The way he brushes his fingers against the back of her neck is, though, along with the way she can't seem to stop her hands from touching him_ somewhere_. And oh god, the _touching_-

The third time it happens, they're studying in the library, because the library is neutral, public ground, and she's so proud of him because he's actually trying. It reminds her of exams in high school and the way he would focus all his energy on her and on the material because he _wanted_ to try. He looks- really, really _handsome_, and she knows what he looks like when he comes (the image in burned into her brain) and she can't control the flush that rises to her cheeks or the way her heart pounds as she stares at his hands and the way his adam's apple bobs as he swallows.

He looks up at her and_ smirks_ and she's suddenly across the chairs in their study carrel, lips smashed against his. It's a _library_, for god's sake, her sanctuary, and she hates that she can't control herself around him. He slides warm hands under her shirt, deftly pushing up her bra. She squirms in his lap and fumbles with his belt. Blunt nails scrape across her nipples, and she muffles her groan in the side of his neck.

He's hot and hard in her hand and he doesn't have time to think because she's already sinking onto him, and he's trying not to whimper into her chest as she rocks against him.

"Case- " his voice is strangled as she rolls her hips, and_ jesus_ they're in a goddamn library and he's never going to be able to come here again without popping a boner. She bites her lip and closes her eyes, fingers clenching at the muscles in his shoulders, and he locks his hands onto her hips and pulls her tight against him, guiding her movements. "Ride me, Case," he murmurs in her ear, so quiet that she can't quite be sure she heard him correctly. Except he's meeting her slow thrusts and_ god_ he's deep and she's shuddering against him, biting his shoulder to keep quiet and he's still talking in her ear, quiet and low and telling her she's amazing as he stiffens and lets go.

She wants to stay where she is, out of breath and glued to him, but common sense rushes back and she awkwardly disengages with Derek's help and tries to tell herself that she's not developing a bad habit.

* * *

Denial works pretty well until time number eight, which is time number three outside of her psych class. By incident number ten, Derek's not sure what to think- other than this is the kind of habit that he doesn't want to break, and Casey's strongly considering counseling, except she_ really_ doesn't want this to stop. But time number ten- time number ten changes something, though she can't articulate just_ what_, and really, she's not sure that she wants to.

She began coming to his games when they started college- most of the time, actually, but she won't ever admit it, and she likes to try and hide out in the top of the stands so he can't pick her out of the crowd. He'll occasionally catch her eye while he's benched, and he deftly ignores the way that he seems to play a little harder when he knows she's watching.

The Gaels pull off the win in the last seconds of the game, thanks to an assist by Derek, and he's got a split eyebrow from an altercation in the second period. He can still feel the adrenaline zipping through his veins, and without his permission, his eyes dart to the crowd as the team makes a victory lap. It's pure chance that he catches her eyes, and he can swear they're an even more brilliant blue than normal. His blood is boiling and he _wants_-

The locker room is boisterous, and he revels in the back slaps and "great game"s that fly around. Even still, it's not quite what he's looking for, and when Roberts grins and announces, "Party at Mikey's," he just smiles and tells them to go on without him. The room clears out faster than he would have thought, a few of the guys giving him knowing looks that he ignores. Derek more than understands the lure of beer and easily impressed puck bunnies. Hell, that would have been him not long ago except he can't stop thinking about those goddamn blue eyes and he hasn't so much as looked at another girl since that first night in his dorm room.

He shakes his head and wonders how the fuck it's come to this- nights spent thinking about Casey's eyes and hair and that thing she does with her hips and that other thing she does with her tongue. Slowly but surely, he starts taking off his gear- gloves and helmet lay discarded on the bench, quickly joined by his shoulder and elbow pads. Dimly, he hears the locker room door swing open as he sits and removes his skates. Careful footsteps stop, and Derek looks up to see Casey leaning against the lockers, eyes fixed on him.

"That was_ barbaric_, Derek. You could have been seriously hurt," she says, and it's the same words she's always used, but there's something else behind them now.

"What are you doing in the locker room, Case?" He says it with his usual smirk, but his mouth is a fucking desert, and she's wearing his practice jersey. She blushes a little and fiddles with the hem of his shirt.

"I got tired of waiting for you in the hall."

His grin widens just a little and sprawls back on the bench. She glares at his self-satisfied expression. "You were waiting for me?"

"I thought you might be hurt," she mutters. "Clearly, it was just wishful thinking."

"Aw, Case," he hauls himself off the bench, kicking aside his skates. "I didn't know you cared."

"Care is perhaps a little strong," she hedges. He doesn't miss the way her eyes trace his torso, or the way she lingers on his eyebrow. His senses are still heightened from the game, and he advances, blood pounding.

"Sure you don't wanna kiss it and make it better?" He's up in her space now, but she doesn't back down, and he thinks that that might be his favorite thing about Casey- she never backs down, and he_ loves_ it, loves that answering challenge in her eyes. She reaches up and turns his head, pressing her lips just to the side of his damaged eyebrow.

"Better?"

"Getting there." He shifts a little closer, and she rests her hands on his hips, fingers skirting the bottom of his shirt. He wants to tangle his fingers in those low pigtails she has and_ tug_, and he's suddenly thankful that she never came to any of his games in high school- he's not sure he would have survived the temptation.

"Poor Derek. Show me where it hurts?"

His breath quickens, and he leans forward, pressing her against the lockers. "Everywhere."

"Is that so?" Casey tugs up on the hem of his shirt eagerly, and Derek obliges, darting in for a quick kiss before lifting his arms. She peels his underarmour off and flings it away, hands greedily tracing sweat-slick muscles. "How's this?" She presses her lips to the side of his neck, trails them down to his collarbone- he can feel with pinpoint accuracy the moment she uses her teeth, scraping them along the bone and lower. His skin feels hypersensitive, and it twitches under her lips and tongue.

"Better," he finally manages, and that's about the time she slips her hands under the edge of his breezers.

"What about under here?"

He swallows and puts one hand over hers, guiding it to the drawstring. His eyes are drawn to the way his hand almost completely covers hers. She gives him a smirk that's painfully reminiscent of his own as clever fingers make quick work of the knots holding up his pants. With a little help, they're sliding off his hips, and Casey slips two fingers down, nails scraping softly against his hipbone and under the elastic of his jockstrap. She bites her lip and looks up at him.

Then she pulls back and lets the elastic snap against his hip. "_Ow_, what the_ fuck_, Case?" Her unrepentant grin should_ not_ make him want to kiss her senseless, goddammit. She laughs at him, and he surges forward, capturing her lips, hands slamming into the lockers behind her. Her mouth is hot and wet and she tastes a little like concession stand popcorn as she fists a hand in his still-damp hair and pulls him even closer. _God_, she feels good, body eagerly rubbing against his and he's going to have a problem in a major way soon. "Shit, Case-Casey, _stop_," he mutters against her lips, and she pulls back, frowning.

"What?" She doesn't like the fact that she actually feels a little hurt. Did she do something wrong?

"Stop thinking so much, keener," he says, teeth nipping at her jaw and neck, "and help me get out of the rest of this gear. Unless you_ want_ my boner strangled-?"

She can't help the faint blush that spreads across her face. Derek stumbles a little as he tries to tug down one sock, and that seems to snap Casey out of her embarrassment. He can hardly take his eyes off of her, and that bolsters her flagging confidence. With a small smile, she sinks down, knees hitting the concrete of the locker room.

"Like this?" she asks, fingers yanking the stretched out cotton down.

"Much better," he grins. Kneepads are next, and Derek fumbles with the straps on the right leg as Casey takes the left, and then it's just her kneeling in front of him and his scattered gear and her warm palm sliding up his thigh to his increasingly uncomfortable jockstrap. Once again, she slips her fingers under the straps and for a moment, Derek holds his breath, expecting the sharp _crack_ of elastic on his skin as she looks up at him, smiling.

Instead, she presses a kiss to the side of his hip and carefully tugs the straps down. His hissed breath is music to her ears. He steps out of the last of his gear, and she grabs the base of his cock firmly, slipping her mouth over the tip, and for a moment, Derek sees stars. He catches himself on trembling arms against the lockers as Casey takes him deeper into her mouth, tongue slipping against him.

He can't resist the urge to press his hips forward, and she gives him a warning glare and a quick squeeze. Derek groans and tries not to clench his hands. Her dark hair bobs temptingly as she sucks him off, one hand bracing hard against his thigh, and it's_ Casey_, and he's always kind of dreamed of this moment, but never really dared to hope. She pulls back slowly, and he thinks that his eyes are going to roll into the back of his head. He wants to continue, wants her hot mouth to slide back over him-

"Case," he rasps, and then he's hauling her to her feet, and she's wrapping her hands around his neck, capturing his lips roughly. He presses against her, fingers tripping over the button of her jeans, yanking down the stubborn zipper because _fuck_ he needs to be closer.

Casey shimmies against him, helping him slide down the tight denim and then she's moaning into his mouth as clever fingers push past her panties. She writhes against his hand and she thinks that there may be a lock digging in her back, but she can't quite find it in her to care because she's probably addicted to the way Derek's hands make her feel. Despite the way he frantically kisses her, his fingers are slow and methodical, and her breath hitches every time he brushes past her clit; it's amazing, but she doesn't want slow and methodical.

She drags her mouth away from his and pulls away slightly. Derek tries to move back in, eyes intent on that little place where her neck meets her shoulder. She giggles a little when he finds it and tries not to moan. "Derek," she mutters.

"Mm?" His hand is still stuck in her pants.

"I need-" her voice is lost in a sharp inhale.

"I need, too," he replies, and she doesn't have to see his face buried in her neck to know that he's smirking at her. Half-heartedly, she punches his shoulder.

"No, jackass. I need you to stop." _That_ pulls him up short, and as fast as he got into her underwear, his hand is gone, and he's very still and very quiet. She wasn't anticipating that reaction, and for a moment is confused. "What-"

"You said to _stop_, Case." His voice is tight, and suddenly, it dawns on her. She's torn between smiling and punching him in the other shoulder.

"I didn't mean it like that, dork," she mumbles. "I just-" she gestures at her jeans, which are halfway down her thighs and restricting her movement.

"Oh." And as fast as he had stopped, he was back in the game. "I can help with that," he offers, hands trailing lightly along her exposed thighs and up underneath the jersey she's wearing. She squirms a little and tries not to laugh.

"Oh, no no no," she says in between giggles. "You're gonna start tickling me and then it's all over, pal." He pouts for a half a second until Casey turns around.

"Aw, come on Case. Shy? It's nothing I haven't seen before."

She glances back over her shoulder and smirks. Derek's mouth goes dry as she hooks her fingers into the edges of her panties and bends at the waist, sliding them down to her jeans. She wriggles a little, pulling the tight material down and off her legs, and he's stuck staring at her pert ass, barely covered by his jersey. The moment she steps out of her pants, he locks his hands around her bare hips and pulls her against him, burying his face into her neck.

She's intensely aware of his skin on hers, the way his erection presses against her- his breath stirring the little hairs on the back of her neck. Warm hands skim up her stomach, passing lightly over her ribs. He doesn't even pause at her bra, just shoves the cups up and palms her breasts, fingers rolling over her nipples. She can't help the stuttered gasp as her spine arches, and Derek's hips rock against her.

"_Fuck_, Case- do you have _any_ idea what you do to me?" he growls it in her ear, and she shudders. She wants to say something clever and witty in response, but there's something about the way he says it that makes her heart pound and her knees weak and dries up her words. Instead, she reaches one hand behind her and curls her fingers into his hair, deliberately grinding back against him. He stifles a moan in her shoulder. "_Please_, Casey."

His voice is urgent and quiet in her ear, and she can't remember the last time he said, "please," and it does something completely ludicrous to her brain and maybe her heart. She slips a hand down between her legs, finds his cock, and slowly rubs against him. He's so_ close_, breath harsh in her ear, and she's enjoying the sensation of him as much as the strangled whimpers he makes. She tilts her hips just so and then he's pressing into her, and it's strange and familiar and so fucking_ good_.

She braces herself on the lockers as Derek sinks into her. He brings one hand down, wrapping it across her stomach and gripping her hip; the other remains firmly attached to her breast. He tries to keep his pace slow and steady, but his blood is pounding in his ears. He's still soaring from the win earlier, and the fact that Casey sought him out, wearing his jersey- he feels powerful, possessive, wanted.

"Ha-_aaaaaaah_, Der-_rek-_-" her voice breaks his name, and shatters the last of his control. He slams into her, grip tightening on her hip as he slides his other hand free to help brace them. He's not going to last long, and he can't bring himself to care because Casey's making these increasingly high-pitched noises that drive him wild, and he can feel her begin to clench around him.

"_Case-_-" His spine bows, stomach clenched, skin aching as he comes with a growl. For a long moment, there is nothing but the sound of their harsh panting. Her arms are trembling slightly and it matches the trembling in her thighs- she feels tired and a little sore, and it feels_ fantastic_. Derek is partially slumped against her back, and she resists the urge to laugh at him.

Somewhat belatedly, she realizes their hands are still brushing, clenched together on the locker.

They shower in the locker room afterwards- quickly and reasonably efficiently, despite Derek's knowing leer and Casey's semi-feigned disgust at the perceived lack of cleanliness. They leave the locker room together, and for a moment, she's worried that they'll find a hall full of people waiting for them, but Derek's grinning widely, and he throws an arm around her shoulders like it belongs there.

"I'm starving," he states, pushing the door open for them.

Casey rolls her eyes. "You're always starving."

"So pizza then? Your treat?"

"I think I've already given you your treat for the evening," she shoots back. She's already figuring out where she wants to get pizza from.

"Casey, Casey, Casey. The evening's just beginning." His voice is low and filled with promise, and she wonders if she's ever going to be able to listen to him without thinking of sex. Somehow, she doubts it. Somehow, she doesn't really mind.

* * *

College goes well. So well in fact that between classes and studying and trysts with Derek, Casey almost forgets about the holidays. Right up until incident number twenty, that is- when they're sated and in Derek's bed, and he's definitely _not_ cuddling because Derek isn't a cuddler, he just likes the way her skin feels against his. His roommate's out for the night, and she reaches for a hastily discarded textbook.

"Keeneeeeer," he mumbles into her hair, and she's torn between smiling and scowling.

"You know, you were studying _with_ me earlier," she says, arching a brow.

"Yeah, but that was before I found something better to do." His tone is suggestive as he walks his fingers over her naked hip and up to her chest. She squirms a little, halfway between being tickled and aroused. "Besides, you know the rule."

She groans. "No books in bed." He reaches over and plucks her textbook out of her hands, and she pouts.

"No books in bed while we're naked," he clarifies.

"But-"

He sighs. "Exams aren't until next week, and you _know_ you're going to ace everything." He intends for it to be teasing, but it comes out sounding almost sincere, and it throws them both for a loop. Casey recovers first and hopes he ignores her blush.

"Oh course I'm going to, but I'm more worried about_ you-_-"

"Caaaase-"

"Der-rek."

"How can I fail when I've got Miss Keener Extraordinaire as my tutor? Besides, we've got a week, and then we're home free and outta here for two weeks." He says it casually, a little excited because hey_ no school_, but what she hears makes her feel panicky.

"Flattery is_ not_ going to get you out of studying," she manages.

She'd forgotten about break. _How_ had she forgotten about break- she wants to curl up into a little corner. She's been so focused on school and studying and...and_ Derek_ that it had completely slipped her mind. What were they going to do? How could they go home and act normal when she knows what Derek looks like when he orgasms, when she knows how to drive him insane, when he knows what she sounds like during oral sex?

This was insane;_ they_ were insane thinking that they could just- have sex whenever they wanted and there not be any consequences. College doesn't offer a blank slate, not when the ties go deeper to a marriage and the sibling growing in her mother's belly.

"Can't blame me for trying," he grins, and she snorts a little. She's not sure how they got to this point. It hadn't been what she intended, but then- she hadn't_ intended_ this at all, and doesn't that just go to show what happens when she doesn't think things through.

"I think you'll find I can blame you for a lot of things, mister." She can't help but smile a little at him, despite the churning fear in her stomach. The worst part is that, laying against Derek in his bed, his fingers still on her skin and his mouth smirking against the back of her neck, she almost doesn't care.

"You know you love it," he murmurs. "I make your life interesting, Casey McDonald."

Her eyes are that inescapable blue as she turns to look up at him, and Derek doesn't resist the impulse to dart in for a quick kiss. She's surprised, but she responds enthusiastically, and he realizes, with his hand on her breast and her skin pressed to his, that he wants incident number twenty-one and twenty-two and kind of wants to stop counting how often they come together and that he just wants to_ be_.

He convinces her to stay the night, and she settles next to him, pushing away her lingering panic. It feels strange and significant, and though neither will ever admit it, they're a little scared.

_Tomorrow_, she thinks._ I'll worry about it tomorrow_.

* * *

She doesn't think about it tomorrow. Well, of course she does because she's_ Casey_ and she's never really been good about turning off her brain when it comes to the big stuff, and if being fuck buddies with her step-brother for a semester doesn't qualify as big, then she doesn't know what does.

But as big as it is, she has finals to worry about and stress over more, and_ Derek's_ finals to worry about and stress over. If she were the paranoid sort, she'd think that he was deliberately studying _more_ just to keep her brain focused on their tests instead of...well, them. Except this is_ Derek_ and after years of living together, he knows that the only things she can't ignore are school and him. She_ knows_ she's being manipulated, but Calculus is on Wednesday, and Derek's helping her through some of the problems in exchange for help with his History, and the problem of Christmas Break has to wait.

He makes her dinner on Friday, after a grueling essay exam for her Comp Lit class. She doesn't even think about the fact that she automatically goes back to his dorm; she just calls him to let her in once she gets to the hand scanner. It takes him less time than normal to get to the door, and Casey raises an eyebrow at him. Derek gives her a little smile as he ushers her in.

"What are you doing?" she asks suspiciously, heading for the stairs. Derek grabs her hand and tugs her in the opposite direction.

"Nothing. Come on, I've got a surprise for you."

"What, in the basement?"

He rolls his eyes. "No, in the attic, Space Case._ Come on_." She grumbles, but lets him take her down into the basement of his dorm. It's an older dorm, and smells a little musty. She remembers clearly how Derek had angled for one of the newer athletic dorms, but his scholarship didn't cover housing the first year, and this was what their parents had compromised on.

"I swear to god, Derek, if you're pulling me down here to do your laundry-"

"_Relax_. I haven't needed you to do my laundry since September." The last thing she's expecting is for Derek to go straight to the kitchen. "I was hoping to already have this upstairs before you got here, but you finished your test early, didn't you?"

She's not sure why that makes her blush, or what he's driving at. "Maybe."

"Keener." Derek shakes his head fondly. "Here." He hands her a bowl of mac and cheese. "Oh well, now you get to help me carry it, instead."

"What's this?"

"Uhhh, mac and cheese?" He scrubs out the pot at lightning speed and leaves it on the counter to dry. "Are you sure all the testing hasn't short-circuited something? You're usually quicker on the uptake." She bristles. Derek is already walking back up the stairs, his own bowl in hand. "Are you coming, or what?"

Casey is quick on his heels, mouth open to ask the question on the tip of her tongue. Derek ploughs ahead, up the stairs fast enough that she can't talk if she wants to keep up. He's unlocking his door as she tries to catch her breath.

"Der-_rek_, what-" The door swings open and he hustles her inside. She's confronted with strings of Christmas lights and music, and her breath catches somewhere in the bottom of her stomach.

"I made you dinner," he says, hopping up onto his bed. There's an air of studied casualness about him. If Casey didn't know him so well, she would have missed it, but he's nervous and covering, and it's kind of completely endearing.

"I-"

"Come on, Case." He pats the bed beside him. "Your mac's gonna get cold, and I got the best Christmas movie to watch."

She clambers up onto his bed and gives him a skeptical look, trying to ignore the way her heart pounds. "Did you? I'm almost afraid to ask."

He grins and presses play on his laptop. "Die Hard, baby." She rolls her eyes.

"That is _not_ a Christmas movie, Derek! That's an action movie!"

"That takes place at Christmas time! It totally counts."

"It's about blowing up Alan Rickman!"

"Not blowing up- _defeating_. Die Hard is about finding your inner strength and overcoming impossible odds."

"You're making that up. What are they teaching you in that Film Studies class?"

He gives her a smug grin. "How to be even more awesome." He nudges her shoulder gently. "Besides, it totally has romance, too."

Casey takes a bite of the mac and cheese Derek made her. It's from a box. She saw Kraft blue in the kitchen garbage, but she can't help but think it's the best thing she's ever eaten- comfort food she didn't know that she needed. Their thighs press against each other as the movie starts, and Casey's heart yo-yos.

This? _This_ is definitely becoming a thing.

* * *

The drive back to London is quiet and a little tense. A lot tense, actually. He still doesn't know why he did it. He remembers getting back to his dorm and thinking about the test he'd just finished, and how Casey would be done with hers soon and then he was in the shitty little kitchen in the basement, making the box of mac n' cheese he'd picked up on a whim one late night.

The problem isn't dinner, Derek knows. He could tell by the small, pleased smile on her face and the way she sat next to him without cajoling- the way she argued, but still curled up and watched Die Hard with him. The problem is this_ thing_ that's been growing between them all semester. He's not really big on the thinking things through, but this takes the cake, even for him. He knows, somewhere in the back of his brain, that he ought to just...stop. This is complicated and kind of strange and Casey (who really may as well be a synonym for complicated), and Derek Venturi doesn't _do_ complicated.

Except he clearly does. Frequently. Loudly. He wants_ her_ like he's never wanted anything before, and it terrifies him because it's not just the sex- amazing and phenomenal as it is. He wants watching movies and dinners and their bickering and studying together. His palms start to sweat just thinking about it. He doesn't do_ this_. He doesn't know _how_, can't even fathom how to approach this with her. She stares out the window of the Prince, fingers tapping idly against her thigh. She isn't even fighting for control of the radio, and it weirds him out.

As much as he wants a..._relationship_ with Casey, he really just wants Casey. This pensive, withdrawn thing worries him because it's just not her. Even when she's upset, she's vibrant and energetic. If whatever it is that they're doing is making her like this- he's not sure he wants it.

They're about a half-hour outside of London when he pulls over. She stops her distracted tapping and shoots him a look.

"Derek?"

He won't look at her. This is hard enough without looking at her and maybe admitting to her the crap that he's just really been able to admit to himself. The palm-sweat isn't helping.

"Casey- we need to t-talk-" the words don't want to come, but he manages. He can tell that, of all the things she might have expected, that was not one of them.

"Do we?" She asks, and she can't believe that_ she's_ the one being avoidant here. Judging by Derek's face, he can't either.

He stares at her for a moment, then lunges across the car to kiss her. It's too much teeth, too wet and sloppy and kind of desperate. In the history of Derek Venturi kisses, it's dismally low on the awesome scale. Casey still kisses him back furiously, groaning low in her throat. It had taken all her willpower the night before not to jump him. He made her dinner, dammit. How is she supposed to resist that?

Except he hadn't pushed the issue, just watched the movie, and occasionally her, and it felt like a_ date_, kinda. She pours her frustration and confusion into the kiss, into_ Derek_, and he returns it. When they break apart, it's reluctantly, and the silence is deafening.

There is something in his eyes that she's never really seen before. It thrills her and scares her. They're both breathing heavily, and finally,_ finally_, she croaks,

"What are we doing?" Four little words that they've never spoken- four words that change _everything_. Whatever this had been before, it was unspoken, unnamed- present but unacknowledged.

"I don't know."

She realizes she's seeing fear; it mirrors her own. "W-what do you_ want_ to do?" Avoidance won't work, not after that kiss, and as much as she can lie and sidestep herself, she can't quite do it when confronted with Derek's piercing gaze fixed on her. He knows what he wants, but he's having a hard time seeing her ever agree to it.

Casey McDonald is built for commitment and long-term boyfriends and marriage, and everything that isn't him. He can't believe that she's gone along with him for this long with this no-strings-attached-unnamed thing. That tells him two things- that she either wants him on whatever terms she can have him, or that he isn't worth dating. Oh yes, he_ knows_ what he wants. But he has no idea what _she_ wants, and he's not sure he can take that leap.

His hand inches towards hers, and she twines her fingers with his without a second thought. He feels like his face is burning, and suddenly wishes he'd never thought to stop the car. "This," he mutters finally, so softly it takes Casey a moment to parse his words. She doesn't say anything for a long while, just sort of examines their hands together, and why oh _why_ did he stop the car? Why did he think this was a good idea? Nothing good ever comes out of the "We need to talk" conversation. He should have just driven home and they could have gone on like nothing was different, maybe fucked in his old bedroom (a fantasy he will never, ever in a million years admit to because the implications make his blood curdle), and possibly in the kitchen while the whole family was out and_ fuck_ he's stupid.

She can see the way his pulse flutters in his neck, and he's staring back out the windshield again. But his hand is still firm and warm in hers, familiar skin just a little rough. He swallows, and really, it's the fear again. Derek is never scared, never afraid. And when he is, it's something_ big_. She's known him too long, has spent too much time over the years dissecting what makes Derek tick to not pick up on all the signs.

Casey swallows her fear and her doubt. "Okay."

"Okay?" his voice doesn't sound like his own, and she resists the bubbling urge to giggle hysterically.

"Okay," she says, and squeezes his hand.

He exhales, and it's only a little shaky. He pulls back into the flow of traffic with Casey's irritated,

"Der-_rek_! You're going to get us killed!" filling the car.

* * *

Their parents' house is as noisy as ever, and it's already decorated for Christmas- something that throws Casey for a little bit of a loop. It's weird to have missed something that was once such a huge part of her life. Unseen, Derek palms the base of her spine reassuringly before being tackled by a shrieking Marti.

Her mother is even _more_ pregnant than the last time Casey had seen her, and she didn't know it was possible for Nora to walk around like that and not burst. Nora shoots her a look when she goes in for a ginger hug.

"I'm not going to pop, Miss Case." She squeezes her eldest daughter tightly, and Casey squeaks and giggles and squeezes her back. "Probably." Derek is next on her list, and Casey watches in amusement as he bears the brunt of her mother's affection with only a moderate rolling of his eyes and protestation. She sees the way his fingers clutch her mother's shoulders just long enough, and she gives him a little smile. He returns it over Nora's shoulder.

They're assaulted in turns by their family, until it's just one huge, laughing mess of hugs and affection, and Derek finds himself pressed against Casey and gives her a crooked grin. She smirks back and doesn't pull away as they're squished together. Their family is too happy to not have a screaming match to think anything of it.

Dinner passes by in a blur, and it's talking over each other and laughter and_ loud_, and Derek didn't realize just how much he had missed this. Under the table, his feet tangle with Casey's while Edwin tries to regale them with tales of a ninth grade goof-off. They don't even have to do dishes afterwards, and Derek settles into his favorite chair while Marti picks out a movie they can all watch. Casey settles into her spot on the couch next to him, and when George comes in with a giant bowl of popcorn, they only have a minor food fight.

It's so familiar, and just a little different because she knows that, as they head upstairs for bed, they're going to brush their teeth and maybe fight a little with Lizzie and Edwin for the bathroom and go into their separate rooms- rooms that feel kind of empty and impersonal now that they've moved out. She thinks that she will probably find some way to kiss Derek goodnight, and that makes her brain sort of fizz pleasantly.

It doesn't go quite that way, though; Lizzie and Edwin both get uninterrupted chances at the bathroom thanks to Marti, who cajoles Derek into reading her a bedtime story. Casey even manages to get her night time routine finished before he's off the hook, and she gives him a small, secretive smile as he comes out of his little sister's room, shutting the door carefully behind him.

"Going to bed?" he asks lowly. They're the only ones in the hall, and he inches just a little too close.

"I was thinking about it," she replies. She smirks. "But you're just so _cute_ with Marti that I had to stay up and watch the show."

"I am_ not_," he protests, failing completely to hide his grin.

"Are _so_. You're just a big softie, Derek Venturi."

"Lies."

"Full of-"

"Don't you dare-"

"-_feeeeelings_," she teases. He makes a huffy little noise in the back of his throat and smashes his lips against hers, backing her across the hallway. Casey fumbles behind her for the doorknob and twists, and together they stumble into Derek's bedroom. He slams the door behind him, never breaking contact, and steers them to his bed. She tumbles back first and bounces a little, and Derek follows.

"I'll show you feelings," he mumbles, mouth hot against her collarbone and neck, nipping lightly at her jaw. He breaks away long enough to rip his shirt over his head.

She squirms against him, hips pressing teasingly into his. "Oh? Is _that_ what that is?"

He makes a noise stuck somewhere in between a laugh and a growl, and sucks hard on that little point just under her jaw. "Casey McDonald, you shameless pervert."

"I learned from the best," she replies, and he would be so proud of her, except she's somehow gotten his jeans undone and has her hand wrapped around his dick and thinking really isn't his highest priority any longer. He shimmies out of his pants and boxers, and _oh_, she feels amazing against him, her hand just warm enough, just slow enough to be tortuous, and he has to resist the urge to fuck into her fist.

Instead, he licks at her collarbones, one hand deftly unbuttoning the flannel pajama top she's got on. It's pink and has snowflakes and is utterly hideous and also, inexplicably, the sexiest thing he's ever seen. She's already foregone her bra in deference to sleep, and he can't stop the words that form before he latches onto a nipple. "I've always dreamed about this."

She stills for just a second. "Really? About what?" Her voice is surprisingly level given the proximity of his teeth to her nipple, and he fixes that with a quick bite. She gasps, "Tell me," and he loves the way that she can still be so bossy, even when he's got his lips and teeth and tongue on her sensitive skin.

He realizes with a start that she _wants_ to hear this, that it's kind of turning her on. He has a choice here, and somewhere between Casey's hitching breath and the way her skin trembles under his fingers, he's decided.

"Taking off your giant ugly pjs," he teases, mouth still full of flesh. She scowls a little and tightens her grip on him. "Wanted to see what you'd be wearing under them," he admits, and tweaks her other nipple. Casey squirms. "Drag your panties down those long legs, kiss every inch of skin- you'd be so _wet_ for me by the time I was finished." She squirms again, and he doesn't miss the way she rubs her thighs together. "It used to drive me insane," he licks along the exposed skin of her stomach, breath tickling, "knowing that you were right on the other side of that wall-"

He's at her hip now, fingers skimming the elastic of her flannel pj pants. "Wondering if you were thinking about me like I was thinking about you." Derek swallows, inching her pajama bottoms down. "Could you hear me, Case?" She lifts her hips for him, and he tugs at her pants and underwear.

"Di-did you-?"

"Hm?" He knows what she wants to ask, but he's not going to let her skim over the question. "Did I_ what_, Casey?"

She shivers at his breath blowing lightly over her damp curls. "_Hng_. Did you touch yourself? Thinking about me?"

He wasn't really expecting her to come right out and say it. He really wasn't anticipating the way it would make his dick ache. "Yes," he hisses.

"Did you think about me going down on you?"

Derek groans and catches Casey's gaze. "Yeah," he says, and the timbre sends shivers through her. "Thought about this, too."

She has just enough time to absorb his words before he's forcefully driving all rational thought from her head with his tongue. She bites back a moan as he licks into her without preamble, and doesn't it just figure that he's as skilled with his tongue at_ this_ as he is with talking.

Derek slips his hands under her thighs, and tugs Casey closer to his mouth. He runs his tongue along her slit and _god_, she's so wet for him. He doesn't want to admit that he's never done this with another girl before, so he listens intently to the myriad of little sobs and sighs Casey makes, pays attention to the way she fists one hand into his hair and tries to grind herself onto his face.

His fingers dig into her thighs as he tries to hold her still, but she's overloaded with sensation. She'd never given much thought to the idea of being eaten out, but right now it's the only thing she can think of. She almost cries when he stops and looks up at her. His mouth is wet as he grins, and she flushes.

Derek reaches up just far enough to grab one of his pillows. He hands it to her and says with a leer, "You might want to use this."

She picks it up and smacks him on the head with it, and Derek laughs and pinches the inside of her thigh lightly in retribution. Before she can react, he's got his mouth sucking on her clit, and she's forced to bury her cry in Derek's pillow lest she wake up the entire house.

Sprawled out on the bed as they are, he's keenly aware of just how much he wants her. His hips press just a little harder into the mattress, struggling for any kind of relief as he risks letting his two-handed grip on Casey go. He nearly gets a black eye for his troubles when he slips two fingers into her and_ sucks_. Even through the pillow, he can hear the high pitched keening noise she makes, her hips twisting and rocking as he drives her to orgasm.

Her brain implodes somewhere between his mouth and fingers and the way he moans against her- like somehow he's enjoying this just as much as she is- and her nerves are burning and singing as she comes violently. She thinks he's maybe smirking, but it's hard to tell, and she's far past caring at this point. Derek swipes at her lazily with his tongue as she comes down from her high. His scalp kind of hurts from Casey's persistent grip, and when she tugs at him once more, he grumbles, but lets her pull him up.

He tastes a little strange when she kisses him, and she pulls back just a little. Derek watches her lick her lips tentatively, his cock twitching as he watches her figure out that what she's tasting is herself. She darts back in to kiss him again, fierce and hard, and he groans into her mouth.

"Case-" his voice cracks over her name.

"I used to think about you, too," she admits softly. Derek is mostly draped over her, and she presses against him in a slow roll from shoulders to toes. She can feel his arms and torso tense, and she smiles just a little. "I used to fantasize about you walking in on me changing or in the shower- about the way you'd touch me..."

"_God_, Casey, _please-_-"

She thinks, as she wraps her legs around his hips, that she's going to be in big trouble if Derek ever realizes that all he has to do is whisper that one little word in her ear. She seems to be completely unable to resist it. He sinks into her, and she bites back a sharp gasp. Her hands lock around him as he rests, buried to the hilt, and she can feel the way his arms tremble under her fingertips. She tightens her grip on his hips with her legs, and he stifles a noise in her neck as she shifts.

"Derek-" It's enough to set him in motion, slipping back and thrusting slow and deep.

His breath is hot against her neck, and he's alternating between catching her lips and murmuring something that sounds a lot like "oh" and "fuck" and maybe "Casey" in a variety of new and inventive ways. She keeps her legs tight, preventing him from pulling out as far as he'd like, but ultimately, he can't bring himself to care because she's _Casey_ and he's _Derek_ and it wouldn't be the same if they didn't struggle against each other _somehow_.

And god, it's _good_, but it's not enough. Carefully, he braces himself with one hand and slides a palm along the back of her thigh and tugs just a little. She resists until he whispers, "Just trust me," and then he's arching her legs up and over his shoulders, and Casey can't think, can't_ speak_. She bites her lip to keep from crying out, and Derek's leaning forward, pressing her knees towards her ears and all she can hear are the little shuddering gasps he makes as he presses into her. His spine begins to tingle, and suddenly she surges up and kisses him hard as she clenches around him, pulling his orgasm from him.

Derek muffles his shout in her neck as his hips jerk wildly, and he's pretty sure Casey just left scores along his back and shoulder blades from her nails. They collapse together on his childhood bed, sticky and warm despite the cool air of the room. Casey can feel the pleasant strain in her thighs, and tomorrow she'll probably be aching, but mostly she just feels...satisfied. Derek's still breathing heavily in her ear, one hand tracing absently along her hipbone, and in a while he will either drag them both from the bed for a shower, or pass out completely. He hasn't decided which seems like the better option just yet.

In the morning, there will be breakfast with the family, and he doesn't doubt that they're going to get a few looks from Edwin and Lizzie, no matter how quiet they tried to be; the thought doesn't bother him in the least. Next to him, Casey rolls over a little, pressing her back against his chest and tangling her hand up with his.

"We should get up," she suggests sometime later. Her voice is hazy, bringing him back from the edge of sleep.

"Mm," he grunts. She tugs a little on his hand and sits up. Derek grumbles and resists, until she straight up pulls him upright.

"Get up lazy. I wanna go to bed, and we're both gross."

"But it's a good gross," he counters. She gives him the eyebrow as she rummages in a bag. "_Fine_," he concedes, and stands. Casey pulls out her robe and shrugs it on, and he notices for the first time that she's left her luggage in his room. At his surprised look, she shrugs a little, and he can just make out her faint blush.

"I-didn't think you'd mind." She tightens the belt and he can hear the uncertainty in her voice. "You don't, do you?"

And the thing is, he really doesn't. He likes that she left her stuff with his, and it doesn't feel like an invasion, it feels right. "Nah. It's cool," he says, and she gives him a little grin.

"Shower?"

He returns her smirk and grabs his own robe. "You bet."

So you know, maybe it_ is_ a thing.


End file.
